Intermediate-Range Nuclear Forces Treatyabbreviation INF Treatynuclear-arms-control accord reached by the United States and the Soviet Union in 1987 in which those two nations agreed to eliminate their stocks of intermediate-range and shorter-range (or “medium-range”) land-based missiles (which could carry nuclear warheads). It was the first arms-control treaty to abolish an entire category of weapon systems. In addition, two protocols to the treaty established unprecedented procedures for observers from both nations to verify firsthand the other nation’s destruction of its missiles.

The INF Treaty defined intermediate-range ballistic missiles (IRBMs) and ground-launched cruise missiles (GLCMs) as those having ranges of 1,000 to 5,500 km (620 to 3,400 miles) and shorter-range ballistic missiles (SRBMs) as those having ranges from 500 to 1,000 km.

The deployment of IRBMs in Europe first became an arms-control issue in the late 1970s, when the Soviet Union began replacing its older single-warhead SS-4 and SS-5 IRBMs with newer and more accurate SS-20s, which could deliver three nuclear warheads apiece from a distance of 5,000 km. Mounted on mobile launchers based in the European part of the Soviet Union, the SS-20s could strike targets anywhere in western Europe in less than 10 minutes.

Under pressure from its western European allies in the North Atlantic Treaty Organization (NATO), the United States in 1979 committed itself to deploying two intermediate-range weapons systems of its own in western Europe: the Pershing II and the Tomahawk cruise missile. Mounted on mobile launchers, the Pershing II was an IRBM that could carry a single nuclear warhead a distance of about 2,000 km and strike within the vicinity of Moscow in less than 10 minutes.

The SS-20 and the Pershing II could deliver warheads to their targets with unprecedented accuracy. They thus had the capability to destroy reinforced command bunkers and missile silos deep within enemy territory. Such missiles, it was argued, were not defensive in nature but were actually destabilizing “first-strike” weapons that directly threatened both the military command structure of NATO and prime targets within the Soviet heartland. This created the political incentive for both sides to curtail such weapons through arms-control negotiations.

INF negotiations began in October 1980, three years after the first SS-20s were deployed in the Soviet Union and three years before the first Pershings and Tomahawks were deployed in western Europe under NATO auspices. The treaty as finally approved was based upon the “zero option” proposed by the United States in November 1981. Under this proposal, NATO would forego forgo deploying its intermediate-range missiles if the Soviets dismantled their SS-20s and the older IRBMs it was replacing. After five years of interrupted and often acrimonious negotiation, the Soviet Union accepted the concept of elimination (rather than mere reduction) of all land-based IRBMs and, in July 1987, expanded it to include a “double-zero” option. This proposal called for the elimination not only of all of the superpowers’ intermediate-range missiles but also of their shorter-range missiles as well. These SRBMs consisted of the U.S. Pershing 1A and the Soviet SS-12 and SS-23. The United States agreed to this proposal. The Soviet Union also agreed to on-site verification of the missiles’ destruction.

The treaty incorporating these commitments was signed in Washington, D.C., on Dec. 8, 1987, by U.S. President Ronald Reagan and Soviet General Secretary Mikhail Gorbachev. It was ratified by the U.S. Senate and the Supreme Soviet the following year.

The INF Treaty called for the progressive dismantling, over three years, of 2,619 missiles, about half of which were deployed at the time of signing. About two-thirds of the missiles affected were Soviet, and the rest were American. Each country was allowed to keep intact the warheads and guidance systems of the destroyed missiles. Also destroyed were missile launchers and various kinds of support equipment and structures. Teams of observers from both countries were given access to certain operating bases, support facilities, and elimination facilities in order to verify the withdrawal and destruction of the missile systems. In order to ensure the permanent elimination of intermediate-range missiles, each country was given the right for 13 years to conduct periodic inspections of operating bases and support facilities and to monitor one production plant at which weapons of the INF category might be produced.